Sound-based prognostics for a combustion air inducer

ABSTRACT

A device is configured to operate a Heating, Ventilation, and Air Conditioning (HVAC) system. The device is further configured to determine that the speed of a combustion air inducer has exceeded a speed threshold value. The device is further configured to receive an audio signal from a microphone while operating the HVAC system, to identify an audio signature for the combustion air inducer from an audio signature library, and to determine the audio signature for the combustion air inducer is present within the audio signal. The device is further configured to determine a fault type based on the determination that the audio signature for the combustion air inducer is present within the audio signal, to identify a component identifier for a component of the HVAC system that is associated with fault type, and to output a recommendation identifying the component identifier.

TECHNICAL FIELD

The present disclosure relates generally to Heating, Ventilation, andAir Conditioning (HVAC) system control, and more specifically tosound-based prognostics for a combustion air inducer.

BACKGROUND

Existing heating, ventilation, and air conditioning (HVAC) systemstypically can only provide a general alert when there is an issue withan HVAC system. For example, the HVAC system may report that an errorhas occurred while trying to operate the HVAC system and that a serviceis required to repair the HVAC system. Existing HVAC systems cannottypically self-diagnose any issues with the HVAC system. This means thata technician will need to inspect the HVAC system and make repairs tothe HVAC system. In many instances, a technician will need to makemultiple trips to a location to first diagnose the issue with an HVACsystem and then to return with the appropriate parts and tools forservicing the HVAC system. This process results in an extended amount ofdowntime while the technician diagnoses and makes repairs to the HVACsystem.

SUMMARY

The system disclosed in the present application provides a technicalsolution to the technical problems discussed above by providing asound-based HVAC diagnostic system that is configured to detect faultsand issues within an HVAC system based on sounds made by the componentsof the HVAC system. The disclosed system provides several practicalapplications and technical advantages which include a process thatenables an HVAC system to self-diagnose faults within the HVAC systemand to output information that identifies any faulty components of theHVAC system and/or instructions for servicing the HVAC system. Thesefeatures reduce the amount of downtime that an HVAC system willexperience because the HVAC system is able to output information thatidentifies the components that are causing the issues that the HVACsystem is experiencing. This process provides a practical applicationthat allows a technician to be prepared with all of the necessaryequipment (i.e. parts and tools) and instructions for servicing the HVACsystem without having to first diagnose the HVAC system themselves.

In addition, existing HVAC systems rely on a manual inspection of anHVAC system for diagnosing issues and faulty components of the HVACsystem. Such a manual process is susceptible to misdiagnosing issueswith an HVAC system or overlooking some faulty components that may needreplacing or servicing. The HVAC system may experience additionaldowntime when an HVAC system is misdiagnosed and/or not all of thecorrect components are serviced. In contrast, the self-diagnosingfeature of the disclosed HVAC system provides a practical applicationthat ensures that the HVAC system will be correctly diagnosed andserviced at the outset which prevents further downtime for the HVACsystem.

In one embodiment, the system comprises a device that is configured todetermine that the speed of a combustion air inducer has exceeded aspeed threshold value while operating an HVAC system. The device isfurther configured to receive an audio signal from a microphone whileoperating the HVAC system, to identify an audio signature for thecombustion air inducer, and to determine the audio signature for thecombustion air inducer is present within the audio signal. The device isfurther configured to determine a fault type based on the determinationthat the audio signature for the combustion air inducer is presentwithin the audio signal, to identify a component identifier for acomponent of the HVAC system that is associated with fault type, and tooutput a recommendation identifying the component identifier.

In another embodiment, the system comprises a device that is configuredto determine that the amount of time to ignite a burner in a burnerassembly has exceeded a time threshold value and that a flame was notdetected by a flame sensor while operating an HVAC system. The device isfurther configured to receive an audio signal from a microphone whileoperating the HVAC system, to identify an audio signature for the flame,and to determine whether the audio signature for the flame is presentwithin the first audio signal. The device is further configured todetermine a fault type based on the determination of whether the audiosignature for the flame is present within the audio signal, to identifya component identifier for a component of the HVAC system that isassociated with fault type, and to output a recommendation identifyingthe component identifier.

In another embodiment, the system comprises a device that is configuredto determine that the amount of time to close a pressure switch exceedsa time threshold value while operating an HVAC system. The device isfurther configured to receive an audio signal from a microphone whileoperating the HVAC system, to identify an audio signature for thecombustion air inducer, and to determine the audio signature for thecombustion air inducer is present within the audio signal. The device isfurther configured to determine a fault type based on the determinationthat the audio signature for the combustion air inducer is presentwithin the audio signal, to identify a component identifier for acomponent of the HVAC system that is associated with fault type, and tooutput a recommendation identifying the component identifier.

In another embodiment, the system comprises a device that is configuredto determine that the speed of a combustion air inducer exceeds a speedthreshold value while operating an HVAC system. The device is furtherconfigured to receive an audio signal from a microphone while operatingthe HVAC system and to determine an audio signature for the combustionair inducer is not present within the audio signal. The device isfurther configured to determine whether an audio signature for theintegrated furnace controller is present within the audio signal. Thedevice is further configured to determine a fault type based on thedetermination of whether the audio signature for the integrated furnacecontroller is present within the audio signal, to identify a componentidentifier for a component of the HVAC system that is associated withfault type, and to output a recommendation identifying the componentidentifier.

In another embodiment, the system comprises a device that is configuredto determine that the amount of time to close a pressure switch exceedsa time threshold value while operating an HVAC system. The device isfurther configured to receive an audio signal from a microphone whileoperating the HVAC system and to determine that an audio signature for acombustion air inducer is not present within the audio signal. Thedevice is further configured to determine whether an audio signature foran integrated furnace controller is present within the audio signal. Thedevice is further configured to determine a fault type based on thedetermination of whether the audio signature for the integrated furnacecontroller is present within the audio signal, to identify a componentidentifier for a component of the HVAC system that is associated withfault type, and to output a recommendation identifying the componentidentifier.

Certain embodiments of the present disclosure may include some, all, ornone of these advantages. These advantages and other features will bemore clearly understood from the following detailed description taken inconjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of an embodiment of an analysis system foran HVAC system;

FIG. 2 is a flowchart of an embodiment of an analysis process for aburner assembly in an HVAC system;

FIG. 3 is a flowchart of an embodiment of a sound-based analysis processfor a combustion air inducer in an HVAC system;

FIG. 4 is a flowchart of an embodiment of a time-based analysis processfor a combustion air inducer in an HVAC system;

FIG. 5 is an embodiment of an analysis device for the HVAC system; and

FIG. 6 is a schematic diagram of an embodiment of an HVAC systemconfigured to integrate with the analysis system.

DETAILED DESCRIPTION System Overview

FIG. 1 is a schematic diagram of an embodiment of an analysis system 100for heating, ventilation, and air conditioning (HVAC) systems 104. Theanalysis system 100 is generally configured to use sound for detectingand diagnosing faults within an HVAC system 104. More specifically, theanalysis system 100 is configured to self-diagnose faults within theHVAC system 104 and to output information that identifies any faultycomponents of the HVAC system 104 and/or instructions for servicing theHVAC system 104. These features reduce the amount of downtime that anHVAC system 104 will experience because the HVAC system 104 is able tooutput information about the components that are causing the issues thatthe HVAC system 104 is experiencing. This process allows a technician tobe prepared with all of the necessary equipment (i.e. parts and tools)and instructions for servicing the HVAC system 104 without having tofirst diagnose the HVAC system 104 themselves.

In one embodiment, the analysis system 100 comprises a thermostat 102, amicrophone 108, and an HVAC system 104 that are in signal communicationwith each other over a network 106. The network 106 may be any suitabletype of wireless and/or wired network including, but not limited to, allor a portion of the Internet, an Intranet, a private network, a publicnetwork, a peer-to-peer network, the public switched telephone network,a cellular network, a local area network (LAN), a metropolitan areanetwork (MAN), a personal area network (PAN), a wide area network (WAN),and a satellite network. The network 106 may be configured to supportany suitable type of communication protocol as would be appreciated byone of ordinary skill in the art.

HVAC System

An HVAC system 104 is generally configured to control the temperature ofa space 118. Examples of a space 118 include, but are not limited to, aroom, a home, an apartment, a mall, an office, a warehouse, or abuilding. The HVAC system 104 may comprise the thermostat 102, afurnace, compressors, blowers, evaporators, condensers, and/or any othersuitable type of hardware for controlling the temperature of the space118. An example of an HVAC system 104 configuration and its componentsare described in more detail below in FIG. 6 . Although FIG. 1illustrates a single HVAC system 104, a location or space 118 maycomprise a plurality of HVAC systems 104 that are configured to worktogether. For example, a large building may comprise multiple HVACsystems 104 that work cooperatively to control the temperature withinthe building.

Microphones

The analysis system 100 may comprise one or more microphones 108. Themicrophones 108 may be positioned at various locations within the HVACsystem 104. The microphones 108 are generally configured to record thesounds that are made by electrical and mechanical components of the HVACsystem 104. For example, a microphone 108 may be positioned proximate oradjacent to an integrated furnace controller (IFC) 602, a relay, a flamesensor 640, a burner 618, a combustion air inducer (CAI) 606, a gasvalve 626, a gas supply 634, a burner assembly 624, a furnace, or anyother component of the HVAC system 104. Each microphone 108 isconfigured to capture audio signals 116 of one or more components of theHVAC system 104. A microphone 108 may be configured to capture audiosignals 116 continuously, at predetermined intervals, or on-demand. Eachmicrophone 108 is operably coupled to the HVAC analysis engine 110 andprovides captured audio signals 116 to the HVAC analysis engine 110 forprocessing.

Thermostat

The thermostat 102 is generally configured to collect sound informationfor various components of the HVAC system 104 while operating the HVACsystem 104 and to diagnosis faults within the HVAC system 104 based onthe sound information. An example of the thermostat 102 in operation isdescribed below in FIGS. 2-4 . In one embodiment, the thermostat 102comprises an HVAC analysis engine 110 and a memory 112. The thermostat102 may further comprise a graphical user interface, a display 508, atouch screen, buttons, knobs, or any other suitable combination ofcomponents. Additional details about the hardware configuration of thethermostat 102 are described in FIG. 5 .

The HVAC analysis engine 110 is generally configured to control theoperation of the HVAC system 104, to receive audio signals 116 from oneor more microphones 108 of the components of the HVAC system 104 whilethe HVAC system 104 operates, and to detect and diagnose faults withinthe HVAC system 104 based on the audio signals 116. An example of theHVAC analysis engine 110 in operation is described in FIGS. 2-4 . Insome embodiments, the HVAC analysis engine 110 may employ hardwareresources from a remote or cloud server to process the audio signals 116to detect and diagnose faults within the HVAC system 104.

The memory 112 is configured to store an audio signature library 114,system information 126, and/or any other suitable type of data. Theaudio signature library 114 comprises information that can be used witha visual representation (e.g. a plot or graph) of an audio signal 116 todetermine whether a fault is present. For example, the audio signaturelibrary 114 may be configured to associate audio signatures 120 withfault types 122 and component identifiers 124. An audio signature 120identifies attributes of an audio signal 116 that can be used todetermine whether a fault is present within the HVAC system 104.Examples of audio signatures 120 include, but are not limited to,waveform profiles or patterns, frequency profiles or patterns, thresholdvalues, or any other suitable type of information that can be used witha plot of an audio signal 116 to determine whether a fault is present.The fault type 122 identifies a particular type of issue that the HVACsystem 104 is experiencing. Examples of fault types 122 include, but arenot limited to, flame sensor faults, gas valve faults, blower faults,motor faults, relay faults, expansion valve faults, or any othersuitable type of fault. Each fault type 122 is linked with a componentidentifier 124 that identifies a component of the HVAC system 104 thatis causing the issue. The component identifier 124 may be a part name, apart number, a serial number, a model number, a barcode, or any othersuitable type of alphanumeric identifier that uniquely identifies acomponent of the HVAC system 104. Examples of using the audio signaturelibrary 114 are described below in FIGS. 2-4 .

The system information 126 comprises information that is associated withthe components of the HVAC system 104. The system information 126 maycomprise instructions for servicing components of the HVAC system 104,information about tools required for servicing components of the HVACsystem 104, information about the physical locations of the componentsof the HVAC system 104, technical specifications for the components ofthe HVAC system 104, and/or any other suitable type of information thatis associated with the components of the HVAC system 104.

Analysis Process for a Burner Assembly

FIG. 2 is a flowchart of an embodiment of an analysis process 200 for aburner assembly 624 in an HVAC system 104. The analysis system 100 mayemploy process 200 to detect and diagnose faults within a burnerassembly 624 of the HVAC system 104 while operating the HVAC system 104.Process 200 enables the analysis system 100 to self-diagnose faultswithin the burner assembly 624 and to output information that identifiesany faulty components of the HVAC system 104 and/or instructions forservicing the HVAC system 104. This process reduces the amount ofdowntime that an HVAC system 104 will experience because the HVAC system104 is able to output information about the components that are causingthe issues that the HVAC system 104 is experiencing. This process allowsa technician to be prepared with all of the necessary equipment (i.e.parts and tools) and instructions for servicing the HVAC system 104without having to first diagnose the HVAC system 104 themselves. Process200 may be implemented by the thermostat 102, the IFC 602, or acombination of the thermostat 102 and the IFC 602.

At step 202, the thermostat 102 sends commands to initiate a heat cycle.Here, the thermostat 102 sends instructions or commands to the HVACsystem 104 to control the operation of the HVAC system 104. For example,thermostat 102 may send a command to the IFC 602 that triggers the IFC602 to ignite a flame for one or more burners 618 in the burner assembly624 in response to a user input requesting heat for a space 118. Thethermostat 102 may send commands to the HVAC system 104 using anysuitable protocol.

At step 204, the thermostat 102 determines whether the time to ignitethe burners 618 in the burner assembly 624 has exceeded a predeterminedtime threshold value. After sending the commands to the HVAC system 104,the IFC 602 begins measuring the amount of time it takes to ignite theburners 618. The IFC 602 then reports the amount of time that haselapsed to the thermostat 102. The thermostat 102 compares the amount ofmeasured time to a time threshold value. The time threshold valuecorresponds with a maximum amount of time for the burners 618 to ignitebefore the thermostat 102 begins troubleshooting the HVAC system 104 forissues related to the burner assembly 624. The time threshold value maybe set to four seconds, six seconds, ten seconds, or any other suitableduration of time. The thermostat 102 terminates process 200 in responseto determining that the time to ignite the burners 618 in the burnerassembly 624 does not exceed the time threshold value. In this case, thethermostat 102 determines that the burners 618 were able to successfullyignite within the predetermined amount of time. In some instances, thethermostat 102 may use the IFC 602 and/or the flame sensor 640 to verifythat a flame was detected and that the burners 618 were able tosuccessfully ignite. This means that the HVAC system 104 is workingproperly and that no troubleshooting is necessary.

Otherwise, the thermostat 102 proceeds to step 206 in response todetermining that the amount of time to ignite the burners 618 in theburner assembly 624 has exceeded the time threshold value. In this case,the thermostat 102 begins the troubleshooting process to identifypotential issues within the HVAC system 104. At step 206, the thermostat102 activates one or more microphones 108. The thermostat 102 activatesthe one or more microphones 108 by transitioning the microphones 108from an inactive state to an active state. In the inactive state, themicrophones 108 are not configured to capture audio signals 116 or tosend audio signals 116 to the thermostat 102 for processing. In theactive state, the microphones 108 are configured to capture audiosignals 116 and to send audio signals 116 to the thermostat 102 forprocessing.

At step 208, the thermostat 102 determines whether a flame has beensensed by the flame sensor 640 of the HVAC system 104. Here, thethermostat 102 checks the flame sensor 640 to determine whether theflame sensor 640 has detected a flame within the burner assembly 624.The thermostat 102 may check the status of the flame sensor 640 usingany suitable technique. For example, the thermostat 102 may determinewhether an electrical signal has been received from the flame sensor640. The electrical signal from the flame sensor 640 indicates that theflame sensor 640 has detected a flame. The thermostat 102 proceeds tostep 210 in response to determining that a flame has been sensed by theflame sensor 640. In this case, the thermostat 102 determines that theburners 618 were able to successfully ignite. However, since the amountof time it took to ignite the burners 618 exceeded the time thresholdvalue, the thermostat 102 will identify potential issues with the HVACsystem 104 that may have caused the delay to ignite the burners 618. Forexample, the thermostat 102 may identify a fault type that is associatedwith the gas supply 634 and/or the burner assembly 624.

At step 210, the thermostat 102 outputs a recommendation to check thegas supply 634 and the burner assembly 624. For example, the thermostat102 may identify component identifiers 124 for the gas supply 634 and/orthe burner assembly 624 and then output a recommendation that includesthe component identifiers 124 and instructions to check the gas supply634 and/or burner assembly 624. In one example, the thermostat 102 mayoutput recommendation by displaying the recommendation on a graphicaluser interface (e.g. display 508) of the thermostat 102. In thisexample, the thermostat 102 allows a user to identify the causes for theissue locally by interacting with the graphical user interface of thethermostat 102. The information associated with the issue may also beaccessible from a user device that is configured to communicate with thethermostat 102. For instance, a user may be able to access theinformation that is associated with the fault using a mobile applicationor an Internet browser on a user device.

In another example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118. In this example, the thermostat 102 allows a user to identify thecauses for an issue remotely. For instance, the thermostat 102 may sendthe component identifiers 124 and other information to a user devicethat is associated with a technician that will service the HVAC system104. This process allows the technician to obtain information about thecomponents that need to be serviced or replaced before the technicianarrives to the space 118. This feature reduces the downtime of the HVACsystem 104 by providing diagnostic information to the technician beforethe technician arrives which reduces the amount of time required todiagnose issues with the HVAC system 104 and to service the HVAC system104.

Returning to step 208, the thermostat 102 proceeds to step 212 inresponse to determining that a flame was not sensed by the flame sensor640. In this case, the thermostat 102 determines whether the burners 618were able to successfully ignite by checking an audio signal 116captured by the microphones 108 for the presence of an audio signature120 that is associated with the flame. At step 212, the thermostat 102determines whether a flame was sensed by the microphones 108. Thethermostat 102 uses the microphones 108 to capture an audio signal 116of the components of the HVAC system 104 while the HVAC system 104 isoperating or while the HVAC system 104 attempts to execute the commandsthat were provided by the thermostat 102. The thermostat 102 may beconfigured to capture the audio signal 116 for any suitable duration oftime. In some embodiments, the thermostat 102 may combine audio signalsfrom multiple microphones that are distributed within the HVAC system104 to form an aggregated audio signal 116. This process allows thethermostat 102 to collect and use sound information for more componentsof the HVAC system 104.

In one embodiment, the thermostat 102 generates a plot of the audiosignal 116. The thermostat 102 may generate any suitable type ofgraphical or visual representation of the audio signal 116 that can beused for detecting and diagnosing faults within the HVAC system 104. Forexample, the thermostat 102 may generate a plot of amplitudes for theaudio signal 116 over time. As another example, the thermostat 102 maygenerate a plot (e.g. a spectrogram) of frequencies for the audio signal116 over time. For example, the thermostat 102 may apply a Fast FourierTransformation (FFT) to the audio signal 116 to generate the spectrogramor plot of the frequencies for the audio signal 116 over time.

After generating a representation of the audio signal 116, thethermostat 102 identifies one or more audio signatures 120 from theaudio signature library 114 based on the commands that the thermostat102 uses to control the operation of the HVAC system 104. In thisexample, the thermostat 102 may identify the audio signatures 120 thatare associated with the flame of the burners 618 in the burner assembly624. The thermostat 102 then compares the audio signatures 120 to theplot of the audio signal 116. The thermostat 102 may compare theattributes of each audio signature 120 to at least a portion of thevisual representation of the audio signal 116 to determine whether theaudio signature 120 is present within the audio signal 116. Thethermostat 102 then determines whether a fault was detected based on thecomparison. For example, the thermostat 102 may be configured to detecta fault when an audio signature 120 is not present within the plot ofthe audio signal 116. In this case, the audio signatures 120 correspondwith attributes that should be present in the plot of the audio signal116 when the components of the HVAC system 104 are operating normally.As another example, the thermostat 102 may detect a fault based on thepresence or absence of specific frequencies within the plot of the audiosignal 116. In this case, an audio signature 120 may correspond with oneor more frequency values. The thermostat 102 uses the audio signatures120 to determine whether the frequency values are present within theplot of the audio signal 116. In this example, the audio signatures 120correspond with attributes that should be present in the plot of theaudio signal 116 when the HVAC system 104 is operating normally.

In some embodiments, the thermostat 102 may be configured to detect afault by analyzing the frequency content of the audio signal 116. Forexample, the thermostat 102 may perform a Fast Fourier Transformation onthe audio signal 116 to identify the frequency content of the audiosignal 116. The thermostat 102 may then determine whether one or morepredetermined frequencies are present within the frequency content ofthe audio signal 116. In this example, the thermostat 102 may detect afault when one or more of the predetermined frequencies are not presentwithin the frequency content of the audio signal 116. In someembodiments, the thermostat 102 may use this process without generatinga visual representation (e.g. a plot) of the audio signal 116.

The thermostat 102 proceeds to step 214 in response to determining thata flame was not sensed by the microphones 108. In this case, thethermostat 102 determines that there is an issue with one or morecomponents of the HVAC system 104. For example, the thermostat 102 mayidentify a fault type that is associated with the gas supply 634 and/orthe burner assembly 624. At step 214, the thermostat 102 outputs arecommendation to check the gas supply 634 and the burner assembly 624.The thermostat 102 may generate the recommendation using a processsimilar to the process described in step 210. For example, thethermostat 102 may identify component identifiers 124 for the gas supply634 and/or the burner assembly 624 and then output a recommendation thatincludes the component identifiers 124 and instructions to check the gassupply 634 and/or burner assembly 624. In one example, the thermostat102 may output recommendation by displaying the recommendation on agraphical user interface (e.g. display 508) of the thermostat 102. Inanother example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118.

Returning to step 212, the thermostat 102 proceeds to step 216 inresponse to determining that a flame was sensed by the microphones 108.In this case, the thermostat 102 determines that there is an issue withthe flame sensor 640 of the HVAC system 104 and identifies a fault typethat is associated with the flame sensor 640. At step 216, thethermostat 102 outputs a recommendation to replace the flame sensor 640.The thermostat 102 may generate the recommendation using a processsimilar to the process described in step 210. For example, thethermostat 102 may identify a component identifier 124 for the flamesensor 640 and then output a recommendation that includes the componentidentifier 124 and instructions to replace the flame sensor 640. In oneexample, the thermostat 102 may output recommendation by displaying therecommendation on a graphical user interface (e.g. display 508) of thethermostat 102. In another example, the thermostat 102 may output therecommendation by sending the information to a device that is locatedoutside of the space 118.

In some embodiments, the thermostat 102 may also output instructions forrepairing the detected fault. After detecting a fault, the thermostat102 may output information about the components of the HVAC system 104that are associated with the fault and/or any other information that canbe used to service the HVAC system 104. For example, the thermostat 102may output a component identifier 124 for any components that areassociated with the detected fault, location information about where theidentified components are located within the HVAC system 104, serviceinstructions for how to repair or replace the identified components,tools for servicing the identified components, and/or any other suitabletype of information that is associated with the identified components ofthe HVAC system 104.

Speed-Based and Sound-Based Analysis Process for a Combustion AirInducer

FIG. 3 is a flowchart of an embodiment of a sound-based analysis process300 for a CAI 606 in an HVAC system 104. The analysis system 100 mayemploy process 300 to detect and diagnose faults associated with the CAI606 of the HVAC system 104 while operating the HVAC system 104. Process300 uses a speed-based and sound-based analysis process that enables theanalysis system 100 to self-diagnose faults associated with the CAI 606and to output information that identifies any faulty components of theHVAC system 104 and/or instructions for servicing the HVAC system 104.This process reduces the amount of downtime that an HVAC system 104 willexperience because the HVAC system 104 is able to output informationabout the components that are causing the issues that the HVAC system104 is experiencing. Process 300 may be implemented by the thermostat102, the IFC 602, or a combination of the thermostat 102 and the IFC602.

At step 302, the thermostat 102 sends commands to initiate a heat cyclefor the HVAC system 104. Here, the thermostat 102 sends instructions orcommands to the HVAC system 104 to control the operation of the HVACsystem 104. For example, thermostat 102 may send a command to the IFC602 that triggers the IFC 602 to activate the CAI 606 of the HVAC system104 in response to a user input requesting heat for a space 118. Thethermostat 102 may send commands to the HVAC system 104 using anysuitable protocol.

At step 304, the thermostat 102 determines whether the CAI 606 hasexceeded a first speed threshold value. After sending commands to theHVAC system 104, the IFC 602 may begin sending speed request to controlthe speed of the CAI 606. The IFC 602 may then check to see if thepressure switch 662 has closed. The IFC 602 may continue to send speedrequest to the CAI 606 until the IFC 602 can determine that the pressureswitch 662 has closed or that a predetermined pressure threshold levelhas been achieved. The IFC 602 reports to the thermostat 102 when thespeed of the CAI 606 has exceeded the first speed threshold value. Inanother example, the thermostat 102 may measure the speed (e.g.rotations per minute (RPM)) of the CAI 606. For instance, the thermostat102 may determine the speed of the CAI 606 using a speed sensor ortachometer. The thermostat 102 then compares the measured speed of theCAI 606 to the first speed threshold value. The first speed thresholdvalue corresponds with a maximum speed for the CAI 606 before thethermostat 102 begins troubleshooting the HVAC system 104 for issuesrelated to the CAI 606. The first speed threshold value may be set toany suitable speed value. For example, the first speed threshold valuemay be set to a value of 3,000 RPM. The thermostat 102 terminatesprocess 300 in response to determining that the CAI 606 does not exceedthe first speed threshold value. In this case, the thermostat 102determines that the CAI 606 is operating properly and that notroubleshooting is necessary.

Otherwise, the thermostat 102 proceeds to step 306 in response todetermining that the CAI 606 has exceeded the first speed thresholdvalue. In this case, the thermostat 102 begins the troubleshootingprocess to identify potential issues within the HVAC system 104. At step306, the thermostat 102 activates one or more microphones 108. Thethermostat 102 activates the one or more microphones 108 bytransitioning the microphones 108 from an inactive state to an activestate. In the inactive state, the microphones 108 are not configured tocapture audio signals 116 or to send audio signals 116 to the thermostat102 for processing. In the active state, the microphones 108 areconfigured to capture audio signals 116 and to send audio signals 116 tothe thermostat 102 for processing.

At step 308, the thermostat 102 determines whether the CAI 606 hasexceeded a second speed threshold value. Here, the thermostat 102 mayuse a process similar to the process described in step 304 to determinewhether the CAI 606 has exceeded the second speed threshold value. Thethermostat 102 compares the current speed of the CAI 606 to a secondspeed threshold value that is greater than the first speed thresholdvalue. The second speed threshold value corresponds with a maximum safeoperating speed for the CAI 606. The second speed threshold value may beset to any suitable speed value. For example, the second speed thresholdvalue may be set to a value of 4,500 RPM. The thermostat 102 proceeds tostep 310 in response to determining that the CAI 606 has not exceededthe second speed threshold value. In this case, the thermostat 102determines that the CAI 606 is operating at a speed that is within themaximum safe operating speed for the CAI 606. However, since the CAI 606is operating at a speed that is greater than the first speed thresholdvalue, the thermostat 102 will identify potential issues with the HVACsystem 104 that may have caused the increase in the operating speed ofthe CAI 606. For example, the thermostat 102 may identify a fault typethat is associated with the combustion air intake 613, the flue pipe612, and/or the condensate drain 616 of the HVAC system 104.

At step 310, the thermostat 102 outputs a recommendation to check thecombustion air intake 613, the flue pipe 612, and/or the condensatedrain 616. The thermostat 102 may generate the recommendation using aprocess similar to the process described in step 210 of FIG. 2 . Forexample, the thermostat 102 may identify component identifiers 124 forthe combustion air intake 613, the flue pipe 612, and/or the condensatedrain 616 and then output a recommendation that includes the componentidentifiers 124 and instructions to check the combustion air intake 613,the flue pipe 612, and/or the condensate drain 616. In one example, thethermostat 102 may output recommendation by displaying therecommendation on a graphical user interface (e.g. display 508) of thethermostat 102. In another example, the thermostat 102 may output therecommendation by sending the information to a device that is locatedoutside of the space 118.

Returning to step 308, the thermostat 102 proceeds to step 312 inresponse to determining that the CAI 606 has exceeded the second speedthreshold value. In this case, the thermostat 102 determines whether theCAI 606 is operating properly by checking an audio signal 116 capturedby the microphones 108 for the presence of an audio signature 120 thatis associated with the CAI 606. At step 312, the thermostat 102determines whether a CAI audio signature 120 was detected by themicrophones 108. The thermostat 102 may determine whether the CAI audiosignature 120 was detected by the microphones 108 using a processsimilar to the process described in step 212 in FIG. 2 . For example,the thermostat 102 may use the microphones 108 to capture an audiosignal 116 of the components of the HVAC system 104 while the HVACsystem 104 is operating or while the HVAC system 104 attempts to executethe commands that were provided by the thermostat 102. The thermostat102 may then generate a plot or representation of the audio signal 116that was captured by the microphones 108. After generating arepresentation of the audio signal 116, the thermostat 102 identifiesone or more audio signatures 120 from the audio signature library 114based on the commands that the thermostat 102 sent to control theoperation of the HVAC system 104. In this example, the thermostat 102may identify the audio signatures 120 that are associated with the CAI606. The thermostat 102 then compares the audio signatures 120 to theplot of the audio signal 116. The thermostat 102 may compare theattributes of each audio signature 120 to at least a portion of thevisual representation of the audio signal 116 to determine whether theCAI audio signature 120 is present within the audio signal 116. Thethermostat 102 then determines whether a fault was detected based on thecomparison.

In some embodiments, the thermostat 102 may be configured to detect afault by analyzing the frequency content of the audio signal 116. Forexample, the thermostat 102 may perform a Fast Fourier Transformation onthe audio signal 116 to identify the frequency content of the audiosignal 116. The thermostat 102 may then determine whether one or morepredetermined frequencies are present within the frequency content ofthe audio signal 116. In this example, the thermostat 102 may detect afault when one or more of the predetermined frequencies are not presentwithin the frequency content of the audio signal 116. In someembodiments, the thermostat 102 may use this process without generatinga visual representation (e.g. a plot) of the audio signal 116.

The thermostat 102 proceeds to step 310 in response to determining thatthe CAI audio signature 120 was detected by the microphones 108. In thiscase, the thermostat 102 determines that there is an issue with one ormore other components of the HVAC system 104. For example, thethermostat 102 may identify a fault type that is associated with thecombustion air intake 613, the flue pipe 612, and/or the condensatedrain 616 of the HVAC system 104. The thermostat 102 may generate therecommendation using the process described in step 310. Otherwise, thethermostat 102 proceeds to step 314 in response to determining that theCAI audio signature 120 was not detected by the microphones 108. In thiscase, the thermostat 102 determines that there is an issue with eitherthe CAI 606 or the IFC 602 that controls the CAI 606.

At step 314, the thermostat 102 determines whether an IFC CAI driveaudio signature 120 was detected by the microphones 108. The thermostat102 may determine whether the IFC CAI drive audio signature 120 wasdetected by the microphones 108 using a process similar to the processdescribed in step 212 in FIG. 2 . In this case, the thermostat 102compares attributes of an audio signal 116 to audio signatures 120 thatare associated with the IFC 602 to determine whether the IFC CAI driveaudio signature 120 is present within the audio signal 116.

The thermostat 102 proceeds to step 316 in response to determining thatthe IFC CAI drive audio signature 120 was not detected by themicrophones 108. In this case, the thermostat 102 determines that thereis an issue with the IFC 602 and identifies a fault type that isassociated with the IFC 602. At step 316, the thermostat 102 outputs arecommendation to replace the IFC 602. The thermostat 102 may generatethe recommendation using a process similar to the process described instep 210 of FIG. 2 . For example, the thermostat 102 may identify acomponent identifier 124 for the IFC 602 and then output arecommendation that includes the component identifier 124 andinstructions to replace the IFC 602. In one example, the thermostat 102may output recommendation by displaying the recommendation on agraphical user interface (e.g. display 508) of the thermostat 102. Inanother example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118.

Returning to step 314, the thermostat 102 proceeds to step 318 inresponse to determining that the IFC CAI drive audio signature 120 wasdetected by the microphones 108. In this case, the thermostat 102determines that the IFC 602 is working properly and that there is anissue with the CAI 606. The thermostat 102 then identifies a fault typethat is associated with the CAI 606. At step 318, the thermostat 102outputs a recommendation to replace the CAI 606. The thermostat 102 maygenerate the recommendation using a process similar to the processdescribed in step 210 of FIG. 2 . For example, the thermostat 102 mayidentify a component identifier 124 for the CAI 606 and then output arecommendation that includes the component identifier 124 andinstructions to replace the CAI 606. In one example, the thermostat 102may output recommendation by displaying the recommendation on agraphical user interface (e.g. display 508) of the thermostat 102. Inanother example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118.

In some embodiments, the thermostat 102 may also output instructions forrepairing the detected fault. After detecting a fault, the thermostat102 may output information about the components of the HVAC system 104that are associated with the fault and/or any other information that canbe used to service the HVAC system 104. For example, the thermostat 102may output a component identifier 124 for any components that areassociated with the detected fault, location information about where theidentified components are located within the HVAC system 104, serviceinstructions for how to repair or replace the identified components,tools for servicing the identified components, and/or any other suitabletype of information that is associated with the identified components ofthe HVAC system 104.

Time-Based and Sound-Based Analysis Process for a Combustion Air Inducer

FIG. 4 is a flowchart of an embodiment of a time-based analysis process400 for a combustion air inducer in an HVAC system 104. The analysissystem 100 may employ process 400 to detect and diagnose faultsassociated with the CAI 606 of the HVAC system 104 while operating theHVAC system 104. Process 400 uses a time-based and sound-based analysisprocess that enables the analysis system 100 to self-diagnose faultsassociated with the CAI 606 and to output information that identifiesany faulty components of the HVAC system 104 and/or instructions forservicing the HVAC system 104. This process reduces the amount ofdowntime that an HVAC system 104 will experience because the HVAC system104 is able to output information about the components that are causingthe issues that the HVAC system 104 is experiencing. Process 400 may beimplemented by the thermostat 102, the IFC 602, or a combination of thethermostat 102 and the IFC 602.

At step 402, the thermostat 102 sends commands initiate a heat cycle forthe HVAC system 104. Here, the thermostat 102 sends instructions orcommands to the HVAC system 104 to control the operation of the HVACsystem 104. For example, thermostat 102 may send a command to the IFC602 that triggers the IFC 602 to activate the CAI 606 of the HVAC system104 in response to a user input requesting heat for a space 118. Thethermostat 102 may send commands to the HVAC system 104 using anysuitable protocol.

At step 404, the thermostat 102 determines whether the time to close apressure switch 662 exceeds a first time threshold value. After sendingcommands to the HVAC system 104, the IFC 602 begins measuring the amountof time it takes to for the pressure switch 662 to close. The IFC 602then reports the amount of time that has elapsed to the thermostat 102.The thermostat 102 compares the measured amount of time to the firsttime threshold value. The first time threshold value corresponds with amaximum amount of time for the pressure switch 662 to close before thethermostat 102 begins troubleshooting the HVAC system 104 for issuesrelated to the CAI 606. The first time threshold value may be set to tenseconds, fifteen seconds, thirty seconds, one minute, or any othersuitable duration of time. The thermostat 102 terminates process 400 inresponse to determining that the time to close the pressure switch 662does not exceed the first time threshold value. In some instances, thethermostat 102 may use the IFC 602 to determine that the pressure switch662 was able to successfully close. In this case, the thermostat 102determines that the CAI 606 is operating properly and that notroubleshooting is necessary.

Otherwise, the thermostat 102 proceeds to step 406 in response todetermining that the time to close the pressure switch 662 exceeds thefirst time threshold value. In this case, the thermostat 102 begins thetroubleshooting process to identify potential issues within the HVACsystem 104. At step 406, the thermostat 102 activates one or moremicrophones 108. The thermostat 102 activates the one or moremicrophones 108 by transitioning the microphones 108 from an inactivestate to an active state. In the inactive state, the microphones 108 arenot configured to capture audio signals 116 or to send audio signals 116to the thermostat 102 for processing. In the active state, themicrophones 108 are configured to capture audio signals 116 and to sendaudio signals 116 to the thermostat 102 for processing.

At step 408, the thermostat 102 determines whether the time to close thepressure switch 662 has exceeded a second time threshold value. Here,the thermostat 102 may use a process similar to the process described instep 404 to determine whether the time to close the pressure switch 662has exceeded the second time threshold value. The thermostat 102compares the current time to close the pressure switch 662 to a secondtime threshold value that is greater than the first time thresholdvalue. The second time threshold value corresponds with a maximum amountof time for the pressure switch 662 to safely close. The second timethreshold value may be set to any suitable duration of time. Thethermostat 102 proceeds to step 410 in response to determining that thetime to close the pressure switch 662 has not exceeded the second timethreshold value. In this case, the thermostat 102 determines that thepressure switch 662 successfully closed before reaching the second timethreshold value. However, since the pressure switch 662 did not closebefore the first time threshold value, the thermostat 102 will identifypotential issues with the HVAC system 104 that may have caused theincrease in the amount of time to close the pressure switch 662. Forexample, the thermostat 102 may identify a fault type that is associatedwith the combustion air intake 613, the flue pipe 612, and/or thecondensate drain 616 of the HVAC system 104.

At step 410, the thermostat 102 outputs a recommendation to check thecombustion air intake 613, the flue pipe 612, and/or the condensatedrain 616. The thermostat 102 may generate the recommendation using aprocess similar to the process described in step 210 of FIG. 2 . Forexample, the thermostat 102 may identify component identifiers 124 forthe combustion air intake 613, the flue pipe 612, and/or the condensatedrain 616 and then output a recommendation that includes the componentidentifiers 124 and instructions to check the combustion air intake 613,the flue pipe 612, and/or the condensate drain 616. In one example, thethermostat 102 may output recommendation by displaying therecommendation on a graphical user interface (e.g. display 508) of thethermostat 102. In another example, the thermostat 102 may output therecommendation by sending the information to a device that is locatedoutside of the space 118.

Returning to step 408, the thermostat 102 proceeds to step 412 inresponse to determining that the time to close the pressure switch 662has exceeded the second time threshold value. In this case, thethermostat 102 determines whether the CAI 606 is operating properly bychecking an audio signal 116 captured by the microphones 108 for thepresence of an audio signature 120 that is associated with the CAI 606.At step 412, the thermostat 102 determines whether a CAI audio signature120 was detected by the microphones 108. The thermostat 102 maydetermine whether the CAI audio signature 120 was detected by themicrophones 108 using a process similar to the process described in step312 of FIG. 3 .

The thermostat 102 proceeds to step 410 in response to determining thatthe CAI audio signature 120 was detected by the microphones 108. In thiscase, the thermostat 102 determines that there is an issue with one ormore other components of the HVAC system 104. For example, thethermostat 102 may identify a fault type that is associated with thecombustion air intake 613, the flue pipe 612, and/or the condensatedrain 616 of the HVAC system 104. The thermostat 102 may generate therecommendation using the process described in step 410. Otherwise, thethermostat 102 proceeds to step 414 in response to determining that theCAI audio signature was not detected by the microphones 108. In thiscase, the thermostat 102 determines that there is an issue with eitherthe CAI 606 or the IFC 602 that controls the CAI 606.

At step 414, the thermostat 102 determines whether an IFC CAI driveaudio signature 120 was detected by the microphones 108. The thermostat102 may determine whether the IFC CAI drive audio signature 120 wasdetected by the microphones 108 using a process similar to the processdescribed in step 212 in FIG. 2 . In this case, the thermostat 102compares attributes of an audio signal 116 to audio signatures 120 thatare associated with the IFC 602 that controls the CAI 606 to determinewhether the IFC CAI drive audio signature 120 is present within theaudio signal 116.

The thermostat 102 proceeds to step 416 in response to determining thatthe IFC CAI drive audio signature 120 was not detected by themicrophones 108. In this case, the thermostat 102 determines that thereis an issue with the IFC 602 and identifies a fault type that isassociated with the IFC 602. At step 416, the thermostat 102 outputs arecommendation to replace the IFC 602. The thermostat 102 may generatethe recommendation using a process similar to the process described instep 210 of FIG. 2 . For example, the thermostat 102 may identify acomponent identifier 124 for the IFC 602 and then output arecommendation that includes the component identifier 124 andinstructions to replace the IFC 602. In one example, the thermostat 102may output recommendation by displaying the recommendation on agraphical user interface (e.g. display 508) of the thermostat 102. Inanother example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118.

Returning to step 414, the thermostat 102 proceeds to step 418 inresponse to determining that the IFC CAI drive audio signature 120 wasdetected by the microphones 108. In this case, the thermostat 102determines that the IFC 602 is working properly and that there is anissue with the CAI 606. The thermostat 102 then identifies a fault typethat is associated with the CAI 606. At step 418, the thermostat 102outputs a recommendation to replace the CAI 606. The thermostat 102 maygenerate the recommendation using a process similar to the processdescribed in step 210 of FIG. 2 . For example, the thermostat 102 mayidentify component identifiers 124 for the CAI 606 and then output arecommendation that includes the component identifier 124 andinstructions to replace the CAI 606. In one example, the thermostat 102may output recommendation by displaying the recommendation on agraphical user interface (e.g. display 508) of the thermostat 102. Inanother example, the thermostat 102 may output the recommendation bysending the information to a device that is located outside of the space118.

In some embodiments, the thermostat 102 may also output instructions forrepairing the detected fault. After detecting a fault, the thermostat102 may output information about the components of the HVAC system 104that are associated with the fault and/or any other information that canbe used to service the HVAC system 104. For example, the thermostat 102may output a component identifier 124 for any components that areassociated with the detected fault, location information about where theidentified components are located within the HVAC system 104, serviceinstructions for how to repair or replace the identified components,tools for servicing the identified components, and/or any other suitabletype of information that is associated with the identified components ofthe HVAC system 104.

Hardware Configuration for an Analysis Device

FIG. 5 is an embodiment of an analysis device (e.g. thermostat 102) ofan analysis system 100. As an example, the thermostat 102 comprises aprocessor 502, a memory 112, and a network interface 504. The thermostat102 may be configured as shown or in any other suitable configuration.

Processor

The processor 502 comprises one or more processors operably coupled tothe memory 112. The processor 502 is any electronic circuitry including,but not limited to, state machines, one or more central processing unit(CPU) chips, logic units, cores (e.g. a multi-core processor),field-programmable gate array (FPGAs), application-specific integratedcircuits (ASICs), or digital signal processors (DSPs). The processor 502may be a programmable logic device, a microcontroller, a microprocessor,or any suitable combination of the preceding. The processor 502 iscommunicatively coupled to and in signal communication with the memory112, display 508, microphones 108, and the network interface 504. Theone or more processors are configured to process data and may beimplemented in hardware or software. For example, the processor 502 maybe 8-bit, 16-bit, 32-bit, 64-bit, or of any other suitable architecture.The processor 502 may include an arithmetic logic unit (ALU) forperforming arithmetic and logic operations, processor registers thatsupply operands to the ALU and store the results of ALU operations, anda control unit that fetches instructions from memory and executes themby directing the coordinated operations of the ALU, registers and othercomponents.

The one or more processors are configured to implement variousinstructions. For example, the one or more processors are configured toexecute HVAC analysis instructions 506 to implement the HVAC analysisengine 110. In this way, processor 502 may be a special-purpose computerdesigned to implement the functions disclosed herein. In an embodiment,the HVAC analysis engine 110 is implemented using logic units, FPGAs,ASICs, DSPs, or any other suitable hardware. The HVAC analysis engine110 is configured to operate as described in FIGS. 1-4 . For example,the HVAC analysis engine 110 may be configured to perform the steps ofprocess 200, 300, and 400 as described in FIGS. 2, 3, and 4 ,respectively.

Memory

The memory 112 is operable to store any of the information describedabove with respect to FIGS. 1-4 along with any other data, instructions,logic, rules, or code operable to implement the function(s) describedherein when executed by the processor 502. The memory 112 comprises oneor more disks, tape drives, or solid-state drives, and may be used as anover-flow data storage device, to store programs when such programs areselected for execution, and to store instructions and data that are readduring program execution. The memory 112 may be volatile or non-volatileand may comprise a read-only memory (ROM), random-access memory (RAM),ternary content-addressable memory (TCAM), dynamic random-access memory(DRAM), and static random-access memory (SRAM).

The memory 112 is operable to store HVAC analysis instructions 506, anaudio signature library 114, system information 126, and/or any otherdata or instructions. The HVAC analysis instructions 506 may compriseany suitable set of instructions, logic, rules, or code operable toexecute the HVAC analysis engine 110. The audio signature library 114and the system information 126 configured similar to the audio signaturelibrary 114 and the system information 126 described in FIGS. 1-4 ,respectively.

Display

The display 508 is a graphical user interface that is configured topresent visual information to a user using graphical objects. Examplesof the display 508 include, but are not limited to, a liquid crystaldisplay (LCD), a liquid crystal on silicon (LCOS) display, alight-emitting diode (LED) display, an active-matrix OLED (AMOLED), anorganic LED (OLED) display, a projector display, or any other suitabletype of display as would be appreciated by one of ordinary skill in theart.

Network Interface

The network interface 504 is configured to enable wired and/or wirelesscommunications. The network interface 504 is hardware device that isconfigured to communicate data between the thermostat 102 and otherdevices (e.g. microphones 108 and the HVAC system 104), systems, ordomains. For example, the network interface 504 may comprise an NFCinterface, a Bluetooth interface, a Zigbee interface, a Z-waveinterface, an RFID interface, a WIFI interface, a LAN interface, a WANinterface, a PAN interface, a modem, a switch, or a router. Theprocessor 502 is configured to send and receive data using the networkinterface 504. The network interface 504 may be configured to use anysuitable type of communication protocol as would be appreciated by oneof ordinary skill in the art.

HVAC System Configuration

FIG. 6 is a schematic diagram of an embodiment of an HVAC system 104configured to integrate with an analysis system 100. The HVAC system 104conditions air for delivery to an interior space of a building or home.In some embodiments, the HVAC system 104 is a rooftop unit (RTU) that ispositioned on the roof of a building and the conditioned air isdelivered to the interior of the building. In other embodiments,portions of the system may be located within the building and a portionoutside the building. The HVAC system 104 may also include coolingelements that are not shown here for convenience and clarity. The HVACsystem 104 may be configured as shown in FIG. 6 or in any other suitableconfiguration. For example, the HVAC system 104 may include additionalcomponents or may omit one or more components shown in FIG. 6 .

The HVAC system 104 comprises a circulation fan 620, a heating unit 622,a return air temperature sensor 638, a discharge air temperature (DAT)sensor 628, a room air temperature sensor 636, the thermostat 102, andan IFC 602. Portions of the HVAC system 104 may be contained within acabinet 604. In some embodiments, the IFC 602 may be included within thecabinet 604. The HVAC system 104 is configured to generate heat and toprovide the generated heat to a conditioned room or space 118 to controlthe temperature within the space 118. The HVAC system 104 is configuredto employ multi-stage or modulating heating control which allows theHVAC system 104 to configure itself to control the discharge airtemperature and to adjust the speed of the circulation fan 620 tofine-tine the discharge air temperature. In one embodiment, the HVACsystem 104 may be configured to achieve a three to one (3:1), a five toone (5:1) turndown ratio, or any other suitable turndown ratio. Aturndown ratio is the operating range of the HVAC system 104, forexample, the ratio of the maximum output to the minimum output.Alternatively, the HVAC system 104 may be configured to achieve anyother turndown ratio as would be appreciated by one of ordinary skill inthe art upon viewing this disclosure.

The circulation fan 620 is a variable speed unit blower that is operablycoupled to the IFC 602. The IFC 602 may adjust the speed of thecirculation fan 620 to control the discharge air temperature ortemperature rise of the HVAC system 104. The circulation fan 620 may beconfigured to operate at 10%, 25%, 50%, 75%, 100%, or any other suitablepercentage of the maximum speed of the circulation fan 620. Thecirculation fan 620 may be located near an air intake 611 of the cabinet604. The circulation fan 620 is configured to circulate air between thecabinet 604 and the space 118. The circulation fan 620 is configured topull return air 656 from the space 118, to provide the return air 656 tothe heating unit 622 to heat the air, and to provide the heated air assupply or discharge air 654 to the space 118.

The heating unit 622 comprises a burner assembly 624 having a pluralityof burners 618, a flame sensor 640, a heat exchanger 610, a CAI 606, apressure switch 662, a condensate drain 616, a gas valve 626, and a gassupply 634. In one embodiment, the heating unit 622 is a single furnace.The heating unit 622 is configured to generate heat for heating air thatis communicated from the circulation fan 620 to the space 118. Theheating unit 622 is configurable between a plurality of configurationsto adjust the amount of heat generated by the heating unit 622. Forexample, the heating unit 622 may be configured to generate 25% 53%,64%, 75%, 100%, or any other suitable percentage of the maximum heatoutput of the heating unit 622.

The burner assembly 624 comprises a gas manifold 660 and a plurality ofburners 618. The burners 618 are configured for burning a combustiblefuel-air mixture (e.g. gas-air mixture) and to provide a combustionproduct to the heat exchanger 610. The burners 618 are connected to thefuel source or gas supply 634 via the gas valve 626. The burners 618 maybe configured to stay active (i.e. on) during operation or to pulse(i.e. toggle between on and off) during operation. A burner 618configured to stay active during operation is referred to as a constantburner 618 and a burner 618 configured to pulse during operation isreferred to as a pulsed burner 618. A pulsed burner 618 has anadjustable duty cycle so that the percentage of the time period that thepulsed burner 618 is active is adjustable. The pulsed burner 618 isconfigured to be toggled or modulated using pulse width modulation(PWM). For example, a pulsed burner 618 may be modulated by the IFC 602using pulse width modulation.

The flame sensor 640 is configured to detect a flame inside of theburner assembly 624. For example, the flame sensor 640 may be configuredto generate an electrical signal (e.g. electrical current) in responseto heat from a flame within the burner assembly 624. In thisconfiguration, the flame sensor 640 will output an electrical signalwhen a flame is detected. Otherwise, the flame sensor 640 will notoutput an electrical signal when a flame is not detected.

The condensate drain 616 is configured to provide an exit route formoisture and fluid from the heating unit 622. Moisture from the heatingunit 622 may be collected from flue gas condensation and drained fromthe heating unit 622 via the condensate drain 616.

The gas valve 626 is configured to allow or disallow gas flow betweenthe gas supply 634 and the gas manifold 660. For example, the gas valve626 may be operable between an off configuration that substantiallyblocks gas flow between the gas supply 634 and the gas manifold 660, alow-fire rate configuration that allows a first flow rate of gas to besupplied to the burners 618, and a high-fire rate configuration thatallows a second flow rate of gas that is higher than the first flow rateto be supplied to the burners 618. The gas supply 634 is configured tostore and provide fuel or gas for the heating unit 622. The gas supply634 is configured to store and provide any suitable combustible fuel orgas as would be appreciated by one of ordinary skill in the art uponviewing this disclosure.

The heat exchanger 610 comprises a plurality of passageways, forexample, a tubular heat exchanger element for each burner 618. The heatexchanger 610 is configured to receive the combustion product from theburner assembly 624 and to use the combustion product to heat air thatis blown across the heat exchanger 610 by the circulation fan 620.

The CAI 606 is configured to draw combustion air 615 into the burnerassembly 624 (i.e. the burners 618) using an induced draft and is alsoused to exhaust waste products of combustion from the HVAC system 104through a vent 608. In an embodiment, the CAI 606 is operable betweentwo speed settings, for example, a low speed that corresponds with thelow-fire mode of operation for the burners 618 and a high speed thatcorresponds with the high-fire mode of operation for the burners 618.The CAI 606 is configured such that the low speed and the high speedcorrespond to the low-fire gas rate and the high-fire gas rate,respectively, to provide gas-fuel-mixture for the low-fire and high-firemodes of the heat exchanger 610. In one embodiment, the air-fuel mixtureis substantially constant through the various heating unit 622configurations.

The pressure switch 662 is configured to sense negative pressuregenerated by the CAI 606 while the CAI 606 is operating. The pressureswitch 662 is configured to be normally open and to close in response toan increase in differential pressure above a predetermined thresholdvalue.

The return air temperature sensor 638 is configured to determine areturn air temperature for the HVAC system 104. For example, the returnair temperature sensor 638 may be a temperature sensor configured todetermine the ambient temperature of air that is returned to or enteringthe HVAC system 104 and to provide the temperature data to the IFC 602.In one embodiment, the return air temperature sensor 638 is located inthe cabinet 604. Alternatively, the return air temperature sensor 638may be positioned in other locations to measure the return airtemperature for the HVAC system 104. For example, the return airtemperature sensor 638 may be positioned in a duct between the cabinet604 and the space 118.

An example of the DAT sensor 628 includes, but is not limited to, a 10KNegative Temperature Coefficient (NTC) sensor. The DAT sensor 628 isconfigured to determine a discharge or supply air temperature of theHVAC system 104. For example, the DAT sensor 628 may be a temperaturesensor configured to determine the ambient temperature of air that isdischarged from the HVAC system 104 and to provide the temperature datato the IFC 602. In one embodiment, the DAT sensor 628 is located in thecabinet 604. Alternatively, the DAT sensor 628 may be positioned inother locations to measure the discharge air temperature of the HVACsystem 104. For example, the DAT sensor 628 may be positioned in a ductbetween the cabinet 604 and the space 118.

The room air temperature sensor 636 is configured to determine an airtemperature for the space 118. For example, the room air temperaturesensor 636 may be a temperature sensor configured to determine theambient temperature of the air of the space 118 and to provide thetemperature data to the thermostat 102. The room air temperature sensor636 may be located anywhere within the space 118. The thermostat 102 maybe a two-stage thermostat or any suitable thermostat employed in an HVACsystem 104 to generate heating calls based on a temperature setting aswould be appreciated by one of ordinary skill in the art upon viewingthis disclosure. The thermostat 102 is configured to allow a user toinput a desired temperature or temperature set point for a designatedarea or zone such as the space 118.

The IFC 602 may be implemented as one or more CPU chips, logic units,cores (e.g. as a multi-core processor), FPGAs, ASICs, or DSPs. The IFC602 is operably coupled to and in signal communication with thethermostat 102, the room air temperature sensor 636, the return airtemperature sensor 638, the DAT sensor 628, the gas valve 626, thecirculation fan 620, and the CAI 606 via one or more input/output (I/O)ports. The IFC 602 is configured to receive and transmit electricalsignals among one or more of the thermostat 102, the room airtemperature sensor 636, the return air temperature sensor 638, the DATsensor 628, the gas valve 626, the circulation fan 620, and the CAI 606.The electrical signals may be used to send and receive data (e.g.temperature data) or to operate and control one or more components ofthe HVAC system 104. For example, the IFC 602 may transmit electricalsignals to operate the circulation fan 620 and to adjust the speed ofthe circulation fan 620. The IFC 602 may be operably coupled to one ormore other devices or pieces of HVAC equipment (not shown). The IFC 602is configured to process data and may be implemented in hardware orsoftware.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated with another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants notethat they do not intend any of the appended claims to invoke 35 U.S.C. §112(f) as it exists on the date of filing hereof unless the words “meansfor” or “step for” are explicitly used in the particular claim.

1. A Heating, Ventilation, and Air Conditioning (HVAC) analysis system,comprising: a combustion air inducer configured to provide combustionair to an HVAC system; a microphone configured to capture an audiosignal of the combustion air inducer; and an analysis device operablycoupled to the microphone, comprising: a memory operable to store anaudio signature library comprising a plurality of audio signatures,wherein: each audio signature identifies one or more attributes for aportion of an audio signal; each audio signature is associated with afault type for the HVAC system; and each fault type is associated with acomponent identifier for a component of the HVAC system; and a processoroperably coupled to the memory, configured to: operate the HVAC system,wherein operating the HVAC system comprises sending a command toinitiate a heat cycle; determine a speed of the combustion air inducer;determine the speed of the combustion air inducer exceeds a speedthreshold value; receive a first audio signal from the microphone whileoperating the HVAC system; determine an audio signature for thecombustion air inducer is present within the first audio signal;determine a fault type based on the determination that the audiosignature for the combustion air inducer is present within the firstaudio signal; identify a first component identifier for a firstcomponent of the HVAC system that is associated with fault type; andoutput a recommendation identifying the first component identifier. 2.The system of claim 1, wherein: the first component identifiercorresponds with a combustion air intake of the HVAC system; and therecommendation indicates to check the combustion air intake.
 3. Thesystem of claim 1, wherein: the first component identifier correspondswith a flue pipe of the HVAC system; and the recommendation indicates tocheck the flue pipe.
 4. The system of claim 1, wherein: the firstcomponent identifier corresponds with a condensate drain of the HVACsystem; and the recommendation indicates to check the condensate drain.5. The system of claim 1, wherein the processor is further configured totransition the microphone from an inactive state to an active stateafter sending the command to heat the space, wherein: the microphone isnot configured to capture the first audio signal while in the inactivestate; and the microphone is configured to capture the first audiosignal while in the active state.
 6. The system of claim 1, whereindetermining the audio signature for the combustion air inducer ispresent within the first audio signal comprises: generating arepresentation of the first audio signal; and comparing the audiosignature for the combustion air inducer to the representation of thefirst audio signal.
 7. The system of claim 1, wherein outputting therecommendation comprises displaying the first component identifier on agraphical user interface.
 8. The system of claim 1, wherein outputtingthe recommendation comprises sending the first component identifier to adevice that is located outside of the space.
 9. The system of claim 1,wherein: the memory is further operable to store instructions forservicing the components of the HVAC system; and the processor isfurther configured to output instructions for servicing the firstcomponent of the HVAC system that is associated with the first componentidentifier.
 10. A Heating, Ventilation, and Air Conditioning (HVAC)analysis method, comprising: operating an HVAC system, wherein operatingthe HVAC system comprises sending a command to initiate a heat cycle;determining a speed of a combustion air inducer, wherein the combustionair inducer is configured to provide combustion air to the HVAC system;determining the speed of the combustion air inducer exceeds a speedthreshold value; receiving a first audio signal from a microphone whileoperating the HVAC system; identifying an audio signature for thecombustion air inducer from an audio signature library comprising aplurality of audio signatures, wherein: each audio signature identifiesone or more attributes for a portion of an audio signal; each audiosignature is associated with a fault type for the HVAC system; and eachfault type is associated with a component identifier for a component ofthe HVAC system; determining the audio signature for the combustion airinducer is present within the first audio signal; determining a faulttype based on the determination that the audio signature for thecombustion air inducer is present within the first audio signal;identifying a first component identifier for a first component of theHVAC system that is associated with fault type; and outputting arecommendation identifying the first component identifier.
 11. Themethod of claim 10, wherein: the first component identifier correspondswith a combustion air intake of the HVAC system; and the recommendationindicates to check the combustion air intake.
 12. The method of claim10, wherein: the first component identifier corresponds with a flue pipeof the HVAC system; and the recommendation indicates to check the fluepipe.
 13. The method of claim 10, wherein: the first componentidentifier corresponds with a condensate drain of the HVAC system; andthe recommendation indicates to check the condensate drain.
 14. Themethod of claim 10, further comprising transitioning the microphone froman inactive state to an active state after sending the command to heatthe space, wherein: the microphone is not configured to capture thefirst audio signal while in the inactive state; and the microphone isconfigured to capture the first audio signal while in the active state.15. The method of claim 10, wherein determining the audio signature forthe combustion air inducer is present within the first audio signalcomprises: generating a representation of the first audio signal; andcomparing the audio signature for the combustion air inducer to therepresentation of the first audio signal.
 16. The method of claim 10,wherein outputting the recommendation comprises displaying the firstcomponent identifier on a graphical user interface.
 17. The method ofclaim 10, wherein outputting the recommendation comprises sending thefirst component identifier to a device that is located outside of thespace.
 18. A Heating, Ventilation, and Air Conditioning (HVAC) analysisdevice, comprising: a memory operable to store an audio signaturelibrary comprising a plurality of audio signatures, wherein: each audiosignature identifies one or more attributes for a portion of an audiosignal; each audio signature is associated with a fault type for an HVACsystem; and each fault type is associated with a component identifierfor a component of the HVAC system; and a processor operably coupled tothe memory, configured to: operate the HVAC system, wherein operatingthe HVAC system comprises sending a command to initiate a heat cycle;determine a speed of a combustion air inducer, wherein the combustionair inducer is configured to provide combustion air to the HVAC system;determine the speed of the combustion air inducer exceeds a speedthreshold value; receive a first audio signal from a microphone whileoperating the HVAC system; determine an audio signature for thecombustion air inducer is present within the first audio signal;determine a fault type based on the determination that the audiosignature for the combustion air inducer is present within the firstaudio signal; identify a first component identifier for a firstcomponent of the HVAC system that is associated with fault type; andoutput a recommendation identifying the first component identifier. 19.The device of claim 18, wherein the processor is further configured totransition the microphone from an inactive state to an active stateafter sending the command to heat the space, wherein: the microphone isnot configured to capture the first audio signal while in the inactivestate; and the microphone is configured to capture the first audiosignal while in the active state.
 20. The device of claim 18, whereindetermining the audio signature for the combustion air inducer ispresent within the first audio signal comprises: generating arepresentation of the first audio signal; and comparing the audiosignature for the combustion air inducer to the representation of thefirst audio signal.